The discovery and demonstration of dynamic nuclear polarization--a personal and historical account.

The paper gives some background about prewar studies of paramagnetic relaxation, the author's postwar measurements of paramagnetic relaxation using 3 cm microwaves, the beginning studies of alkali metal NMR at Illinois, Overhauser's arrival and proposal, the discovery of the ESR of conduction electrons, the experiment confirming his idea in Li and Na metals, then in solutions of Na atoms in liquid ammonia, and the realization that a form of Overhauser effect might be seen when several isotopes were present in cases where atoms were mobile. Two other experiments at Illinois inspired by the Overhauser experiments are briefly described: measurement of the spin susceptibility of conduction electrons and measurement of spin-lattice relaxation times in superconductors.